CAREER: Coded Caching for Wireless Content Delivery Networks: Challenges and Opportunities

对宽带数据的持续增长的需求已经产生了压倒性的网络业务，并且尽管无线通信技术稳步改进，但数据速率仍然达不到需求的指数增长。因此，基于网络特性、需求概况和内容类型的机会传输策略可以帮助满足期望。这种流量爆炸的主要贡献者是宽带视频，其特征在于被多个用户重复请求并且具有高度变化的时间流量。这样的属性提供了在网络的非高峰时间期间将数据高速缓存在更靠近用户的本地存储单元处的机会，以减少高峰时间的网络流量。编码缓存的最新发展为高数据速率提供了一个有前途的解决方案。本研究将研究在实际通信网络中采用缓存的挑战和好处，并为采用缓存作为数据传输网络中的通用资源奠定坚实的理论基础。本项目将通过解决几个实际问题，针对数据传输网络中缓存的基本理论和实践方面。当缓存增益在具有时变信道、异步和延迟敏感请求的真实的网络中降低并且没有中央协调器时，编码技术将用于提高缓存增益。此外，率失真理论框架将被开发来表征高速缓存大小、传输速率和重构质量之间的基本权衡，以及实现这种权衡的有效编码方案。随着多天线通信系统的成功，缓存增益和空间分集之间的相互作用将被研究。这一部分的成功完成将导致一个最佳的资源（缓存大小，功率和速率）分配，以及在非同构多输入多输出（MIMO）网络中的传输调度。最后，将开发用于广泛网络和应用的模拟缓存技术的软件，并支持研究和教育。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The continuously increasing demand for broadband data has produced overwhelming network traffic and, despite steady improvements in wireless communication technology, data rates continue to fall short of the exponential growth in demand. As such, opportunistic transmission strategies based on network characteristics, demand profile, and content type, can help meet expectations. The major contributor to this traffic explosion is broadband video, characterized as being repeatedly requested by multiple users and having highly variant temporal traffic. Such properties provide an opportunity for caching the data at local storage units closer to users during the off-peak hours of the network, to reduce network traffic at peak hours. Recent developments in coded caching offer a promising solution for high data rates. This research will study challenges and benefits of employing caching in practical communication networks, and pursue a solid theoretical foundation for adopting caching as a universal resource in data delivery networks. This project will target the fundamental theory and practical aspects of caching in data delivery networks by addressing several practical concerns. While caching gain degrades in real networks with time-varying channels, asynchronous and delay sensitive requests, and without a central coordinator, coding techniques will be used to improve the gain of caching. In addition, a rate-distortion theoretic framework will be developed to characterize the fundamental trade-off between cache size, delivery rate, and reconstruction quality, alongside efficient coding schemes to achieve this tradeoff. Following the success of multi-antenna communication systems, the interaction between caching gain and spatial diversity will be studied. A successful completion of this part will lead to an optimum resource (cache size, power, and rate) allocation as well as transmission scheduling in non-homogeneous Multi-Input-Multi-Output (MIMO) networks. Finally, software to simulate caching techniques for a wide range of networks and applications, and supporting both research and education, will be developed.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.